Should Craft be an Untrained Skill?

As I got thinking about the Craft skill today, I have begun to wonder if it shouldn't be an Untrained Skill. While I realize that could be complicated - certainly doing some crafts can only be done with some expertise, some of the basics would seem to be able to be done by just about anyone.

For example, in the PG (p. 112) we see that it's a TN 5 to cook a simple, nutritious meal or sew on a button.

I would think that MOST characters could do such a thing, given enough time and effort.

I suppose that any Narrator could grant those simple tasks to any player trying to do them, but I got thinking about a character trying to cobble together/build a simple lean-to or shack in a wilderness environment (like Survival). I suppose, if it were a simple enough task, it wouldn't really even need a skill roll at all. But it just seems like - with these simple instructions spelled out (cooking a meal and sewing on a button) - that just about any character should be allowed to attempt these things.